.active {
  color: red !important;
}
footer {
  position: fixed;
  left: 0;
  bottom: 0;
  line-height: 50px;
  height: 50px;
  width: 100%;
  text-align: center;
  background-color: #333;
  ul {
    list-style: none;
    display: flex;
    li {
      /* 平分 */
      flex: 1;
    }
  }
}
.main {
  padding-bottom: 50px;
}
